it returns theobject ID; otherwise, it returnsNULL. We can use theCOALESCE()function to convert this result into a boolean value. However,this approach returnstrueif any database object with that name exists in the schema, not just a table. ...
When I need to check if a table exists in PHP, I select something from that table trapping the error with '@' if it doesn't exit. For instance: $result=@mysql_query('select * from tb2check limit 1', $handle); if ($result) { // table exists mysql_free($result); } ...
if exists(select * from sysobjects where name=约束名) alter table 表名 drop constraint 约束名; go alter table 表名 add constraint 约束名 check(约束规则),constraint 约束名 check(约束规则); go 示例: -- 添加一个默认约束 use testss; go if exists(select * from sysobjects where name='check1...
if exists(select * from sysobjects where name=约束名) alter table 表名 drop constraint 约束名; go alter table 表名 add constraint 约束名 check(约束规则),constraint 约束名 check(约束规则); go 示例: -- 添加一个默认约束 use testss; go if exists(select * from sysobjects where name='check1...
在MySQL 8.0.16以前,CREATE TABLE允许从语法层面输入下列CHECK约束,但实际没有效果: CHECK (expr) 1. 在MySQL 8.0.16,CREATE TABLE添加了针对所有存储引擎的表和列的CHECK约束的核心特性。CREATE TABLE允许如下针对表或列的约束语法: [CONSTRAINT [symbol]] CHECK (expr) [[NOT] ENFORCED] ...
SQL 2005+ EXECUTE master.sys.sp_MSforeachdb 'USE [?]; if exists(select * from INFORMATION_SCHEMA.tables where TABLE_TYPE=''BASE TABLE'' and TABLE_NAME=''DB_BACKUP_LOG_T'') begin print ''exist in '' + db_name() end' SQL 2000 ...
stuDBgoif exists(select * from Sysobjects where name = 'stuInfo')drop table stuInfogocreate ...
SQL Query to return the data? 1 SELECT TABLE_NAME FROM DBName.INFORMATION_SCHEMA.Tables WHERE TABLE_NAME='Article'How do I check this in C#?As for how you check that in C#? You just make sure the Row count returned from the query is 1. See this article I have already posted. How ...
In MSSQL, checking for column existence is commonly achieved using theINFORMATION SCHEMA – COLUMNSview.Let’s create an.sqlfile to setup the query: $ cat CoulmnTest.sql Use University; ifexists(select*fromINFORMATION_SCHEMA.columnswheretable_name='Course'andcolumn_name='textbook') ...
CREATE PROCEDURE `zz_test_table_detect` () DETERMINISTIC BEGIN DECLARE is_it_there BOOLEAN; DECLARE function_succeeded BOOLEAN; SET is_it_there = does_table_exist ( 'religion', 'choice' ); IF is_it_there = true then SET is_it_there = does_table_exist ( 'religion', 'choice...